#include <sys/wait.h>
#include <unistd.h>
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <errno.h>
int main(){
    int status;
    printf("%s\n", strerror(errno));
    if((status = system("date")) < 0){
        printf("system date error\n");
        exit(0);
    }

    if((status = system("nocommand")) < 0){
        printf("system nocommand error\n");
        exit(0);
    }

    if((status = system("who; exit 44")) < 0){
        printf("system who; exit 44 error\n");
        exit(0);
    }

    exit(0);
}